I generally love everything digital. But I can't get behind online reviews...
If they're all positive, they can bring in A LOT of business. But they seldom are. No matter how good your shop is, there are going to be loud, vindictive complainers.
Assume the average job is $200. And assume 100 people read that one negative review and decide against giving you their business. Well, that's $20,000 lost all because of one jerk.
These people have all the leverage and they know it.
Only thing we can do is what @Peter Pittel did, and respond with a kindly worded, common-sense explanation -- and hope potential customers read it.
If we ignore it, their version becomes truth. And if we respond angrily, we come across as having bad customer service.